Irritable bowel syndrome is the most common gastrointestinal complaint for which patients seek medical care, and may afflict as much as 20 percent of the population to some degree. Studies indicate that patients with irritable bowel syndrome constitute a large portion of a primary care physician's practice (about 12 percent of all patient visits) and account for more than 25 percent of all gastrointestinal referrals. It is estimated that 2.4-3.5 million physician visits per year are related to IBS. IBS has been a diagnosis of exclusion obligating the patient to undergo a series of expensive tests such as endoscopy, complete blood counts, liver function tests, serum electrolytes, erythrocyte sedimentation rate, urine analysis, stool cultures and X-ray studies. If these studies are all negative, the diagnosis of IBS may be given to the patient. Often the patient is not satisfied and seeks care from another physician who repeats this expensive study. We have found that an inexpensive and non-invasive computerized time series analysis of bowel sounds can provide for the first time a practical test with a positive result distinguishing IBS patients from normal subjects or patients with Crohn's disease. The objective of this Phase II project is to confirm the clinical accuracy and usefulness of this test with a large prospective group of undiagnosed patients presenting with abdominal pain. In addition, we will investigate some basic parameters which may influence the test results, such as circadian rhythm and the menstrual cycle in female patients. PROPOSED COMMERCIAL APPLICATION: This product will be used in the diagnosis of irritable bowel syndrome which afflicts as much as 20 percent of the population in the United States. The primary customers will be gastroenterologists, internal medicine and family practice physicians, as well as hospitals and clinics. The primarily software product will be very economical and should result in quite large savings in overall resource utilization. This economical incentive along with patient benefit will result in a successful commercial development.